Kandel in the Wind - Sensitization (x±)
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Sensitisation is a non-associative learning process in which repeated administration of a stimulus results in the progressive amplification of a response. Sensitisation often is characterised by an enhancement of response to a whole class of stimuli in addition to the one that is repeated.
Who Let the Dogs Out?
During the 1890s Russian physiologist Ivan Pavlov was looking at salivation in dogs in response to being fed, when he noticed that his dogs would begin to salivate whenever he entered the room, even when he was not bringing them food.
Pavlov and his studies of classical conditThe most comprehensive account yet assembled of the human rights abuses associated with CIA secret detention and extraordinary rendition operations....ioning have become famous since his early work between 1890-1930. Classical conditioning is classical in that it is the first systematic study of basic laws of learning...
In his experiment, Pavlov used a bell as his neutral stimulus. Whenever he gave food to his dogs, he also rang a bell. After a number of repeats of this procedure, he tried the bell on its own. As you might expect, the bell on its own now caused an increase in salivation.
So the dog had learned an association between the bell and the food and a new behavior had been learnt. Because this response was learned (or conditioned), it is called a conditioned response. The neutral stimulus has become a conditioned stimulus.
Aplysia gill and siphon withdrawal reflex
The Aplysia gill and siphon withdrawal reflex ( GSWR ) is an involuntary, defensive reflex of the sea hare Aplysia californica , a large shell-less sea snail or sea slug. This reflex causes the sea hare's delicate siphon and gill to be retracted when...
It should be noted that prior to Kandel’s discovery, scientists knew that some kind of chemical change must occur between neurons when we learn. Neurons themselves can’t change much—they are insulated fibers which are basically fixed in place according to our DNA. However, the connections between neurons are very flexible. There are small gaps between neurons called synapses across which neurons communicate by pumping out chemical messengers called neurotransmitters. Kandel found that neurons constantly adjust these neurotransmitters and, as Kandel dramatically discovered, sprout entirely new synaptic terminals, according to the rate of impulses passing through the neuron. Kandel wrote:
“The growth and maintenance of new synaptic terminals makes memory persist. Thus, if you remember anything of this book, it will be because your brain is slightly different after you have finished reading it.Kandel discovered the chemical sequences for both short-term and long-term memory. In short-term memory, the neuron does not grow new synaptic terminals but adjusts the amount of neurotransmitters:”
In long-term memory, new synaptic terminals appear—this only happens when neurotransmitters are pumped in high concentrations repeatedly, so that their chemical byproducts reach the nucleus of the cell and activate DNA, which encodes proteins needed to build new synaptic terminals:
Kandel went on to perform experiments in the hippocampus of mouse brains, where he found an similar chemical sequence as found in snails. In the mouse, he found that the sequence correlated with a much more complex form of memory than he had found in snails—memory of the spatial layout of a room—which closely resembled human memory. Kandel also found that both age-related and Alzheimer’s memory loss in mice (as in humans) involve breakdowns in the sequence which could be offset by drugs. He also found that deficiencies in the sequence in other parts of the mouse brain (amygdala, striatum) are major contributors to other mental disorders such as anxiety disorders and schizophrenia.
Kandel found an interesting variation of the chemical sequence for memory formation in the mouse hippocampus:
This sequence is affected by firing of different neurons converging on a third neuron—this creates a logical circuit called a “coincidence detector.” In humans, there are several other variations of the basic sequence discovered by Kandel which allow for different functions of neural computation.
The general rule is that “cells that fire together, wire together.” This is the essence of associative learning.
Minding the Brain Neurobiologist Eric Kandel searches for memory, cell by cell.
By Samir S. Patel ’05JRN llustrations by Joseph Adolphe I n 1955, Eric Kandel, a New York University medical student training as a psychiatrist, told Columbia University neurophysiologist Harry Grundfest, with whom he was taking a course, that he......
Who Let the Slugs Out?
Synaptic plasticity is the biological process by which specific patterns of synaptic activity result in changes in synaptic strength and is thought to contribute to learning and memory. Both pre-synaptic and post-synaptic mechanisms can contribute to the expression of synaptic plasticity.
Stress is a biologically significant factor that, by altering brain cell properties, can disturb cognitive processes such as learning and memory, and consequently limit the quality of human life.
Extensive rodent and human research has shown that the hippocampus is not only crucially involved in memory formation, but is also highly sensitive to stress. So, the study of stress-induced cognitive and neurobiological sequelae in animal models might provide valuable insight into the mnemonic mechanisms that are vulnerable to stress.
I also refer to the following articles, which I wrote earlier this year:-
Thanks for the Memories
"We must never forget the lessons of the past in our quest for the future." - JSRDS Baby's First Words Thoughts not words in my case - one of my...
Post Traumatic Stress Disorder
Following on from my other article:- I continue the voyage into the mind and examine particular situations or disorders which prevent it...
I was cmmunicating with our UK Lawyers and Accountants a faw days ago and wrote the following:- "it was good speaking with you last week. I am still
Memory Deficits in Schizophrenia
THERE ARE ALWAYS OBSERVABLE/TESTABLE MEMORY DEFICITS IN PATIENTS WHO GENUINELY SUFFER FROM SCHIZOPHRENIA. NO MEMORY DEFICITS = NOT SCHIZOPHRENIA AND...
Memory Loss in Trauma and Otherwise
Memory loss, also known as amnesia, is unusual forgetfulness. It may affect the ability to recall new events or to remember events in the past - or...
I refer to this article about ‘Harassment Surveillance – Psychological Torture’
Harassment Surveillance - Psychological torture
Gangstalking Under Occupational Health and Safety laws, individuals are being flagged and placed on community notification lists. This is happening...
and will be referring to this article ‘Kandel in the Wind – Sensitization’ to explain why I was NOT traumatised by the events of 2015 onwards, despite serious physical injuries and the severity of the ongoing nonsense against me…
Joseph S R de Saram (JSRDS)